In this learning activity you'll factor problems using the difference of two perfect squares.

In this screencast, you'll review definitions of To, Too, and Two and review practice sentences.

In this interactive object, learners demonstrate the proper tightening sequence for mechanically joining two mating surfaces.

Learners examine the basic types of dimensioning including unidirectional and aligned systems, and linear, aligned, angled, arrowless, chain, datum, chart, tabular, radius, diameter, typical, and reference dimensions.

The student reviews definitions of to/too/two and completes a practice exercise.

In this animated object, learners examine the signals produced by sourcing and sinking two-wire sensors. A brief quiz completes the activity.

2D and 3D views used to help convey information from a drafter or designer to the welder are provided. This activity will focus on a mounting wedge. A short quiz to test your ability to correctly read this information follows.

The learner will understand the two methods used to create a phase shift in current between two windings.

Learners examine how the two-roll metering system works.

Learners complete two exercises. In the first quiz, they divide viruses into two categories: RNA and DNA. They later match each virus with the disease it causes.

In this interactive object, students explore the basic elements and common terms associated with dimensions and leaders. A quiz completes the activity.

In this learning activity you'll solve systems of two linear equations in two unknowns by determinants.

In this animated activity, learners observe how a two-roll metering system operates.

In this interactive object, learners examine the neuron pathway into and out of the spinal cord. They complete the activity by testing their knowledge of vocabulary and the location of spinal cord structures.

In this animated activity, learners examine how organs are visualized in three dimensions. The terms “longitudinal,” “cross,” “transverse,” “horizontal,” and “sagittal” are defined. Students test their knowledge of the location of abdominal pelvic cavity organs in two drag-and-drop exercises.

In this learning activity you'll explore family structure then enter terms in a grid identifying if that family structure is determined by females, males, or both.

Learners study two diagrams of the lymphatic system and then test their knowledge in drag-and-drop exercises.

In this animated and interactive object, learners examine the voltages that develop across two series zener diodes, which are connected in opposite directions, when DC and AC voltages are applied across them. A brief quiz completes the activity.

Learners review Ohm's Law and then work 12 problems. In each of the problems, students are given two of the three variables (voltage, resistance, or current) and are asked to solve for the third.

In this animated and interactive object, learners study how a DC circuit, consisting of a diac, a capacitor, and two resistors, causes a light-emitting diode to turn on and off. A brief quiz completes the activity.